The expected increase in environmental lead levels raises the pressing question of the effects of lead intake on children. This project studies the effects of lead accumulation on neuropsychological development. To do this, longitudinal neuropsychological, behavioral, and biomedical data collected prospectively by the National Collaborative Perinatal Study and assessment of current neuropsychological functioning will be utilized. Analyses of lead content in the primary and secondary dentine of subjects' exfoliated second deciduous molar teeth will provide an index of lead intake. By integrating these two sets of data, we can determine whether lead intake at various ages, singly or in concert with other developmental events, produces deficits in neuropsychological functioning in children.